This invention relates to a device which is interposable between a dial gauge indicator and a workpiece to facilitate the taking of a plurality of similar measurements. The device readily receives various adapters for making measurements similar to those depicted in U.S. Pat. Nos. 3,101,551 and 3,225,447, to I. E. Bryant, thereby increasing the measuring capabilities of the dial gauge indicator.
Dial gauge indicators are precision measuring instruments well known among machinists. A typical gauge has a face divided into one hundred increments, an indicator plunger which is movable into the gauge a distance of one inch, and, a dial or pointer which indicates movement of the plunger on the face. The dial completes one revolution on the face of the gauge for every one-tenth inch of plunger movement to enable the user to measure one-thousandth of an inch or less. A second, smaller dial, is often employed with a scale indicating tenths of an inch to count revolutions of the main dial when measuring distances exceeding one-tenth of an inch.
Although the foregoing dial gauges are widely used by machinists, it is often bothersome to watch both dials to determine measurement to the nearest tenth of an inch before taking the precise measurement to the desired thousandth of an inch. Moreover, the internal mechanism of these gauges are relatively delicate and it has been experienced that repeated thrusting of the plunger a distance of several tenths of an inch or more can cause undue wear of the gauge reducing its accuracy and eventually its useful life. For example, in the measurement of a one-half inch bore, the dial is driven around the face between four or five revolutions before the actual measurement may be taken. If a plurality of these measurements are repeatedly made, such as by an inspector, the gauge is subjected to at least four unnecessary revolutions of the dial per use.
By employing the device described hereinbelow, it is possible to adjustably preselect and maintain a single one-tenth inch increment within which to take a plurality of similar measurements, i.e., in the above instance the gauge would be set to measure between 0.4 inches and 0.5 inches and at rest would not indicate less than 0.4 inches. Devices which purport to perform a similar function have been described in U.S. Pat. Nos. 2,667,701, to A. G. Davis, and 3,192,635, to C. E. Miles. However well these devices may in fact operate, it is believed that the preferred embodiments set forth herein represent a new and novel improvement in the art.